Discomfort, Pressure Distribution and Safety in Operator's Seat-A Critical Review

Overall seating comfort is influenced by both static and dynamic characteristics of seat system. Therefore, the present study is an overview of work related to comfort in seat-operator interface affected by static and dynamic pressure distribution, and other related parameters involved in seat comfort, low back pain, seat design and safety in seats. A critical review has been presented on the subject, with a purpose to provide quick reference for the future researchers . The studies revealed that seat-human interface pressure on the soft seat is more evenly distributed on a larger effective contact area than on a rigid seat. The pressure distribution at human seat interface of a rigid seat is affected by seat height, posture, type of cushion and frequency and vibration. The dynamic pressure at interface is nearly sinusoidal in the vibration range of 1-10 Hz. Under vibration excitation, increase in excitation magnitude causes increased maximum ischium pressure and maximum effective contact area around resonant frequency of 4.5 to 5.0 Hz. Postural stress, whole body vibration and shocks are recognised as important factors, causing low back pain. This however, can be reduced by provision of lumbar support, side support and suitable cushion type.

[1]  J D Troup,et al.  Driver's back pain and its prevention. A review of the postural, vibratory and muscular factors, together with the problem of transmitted road-shock. , 1978, Applied ergonomics.

[2]  C F Abrams,et al.  Application of a damped spring-mass human vibration simulator in vibration testing of vehicle seats. , 1969, Ergonomics.

[3]  V K Tewari,et al.  Optimum seat pan and back-rest parameters for a comfortable tractor seat , 2000, Ergonomics.

[4]  Hilkka Riihimäki,et al.  Intervention on seat adjustment among drivers of forest tractors , 1997 .

[5]  J. A. Lines,et al.  Whole Body Vibration During Tractor Driving , 1995 .

[6]  J. Matthews.  Ride comfort for tractor operators , 1966 .

[7]  M J Griffin,et al.  Qualitative models of seat discomfort including static and dynamic factors , 2000, Ergonomics.

[8]  R. M. Stayner,et al.  Tractor ride vibration simulation as an aid to design , 1984 .

[9]  Leonard C. Mead,et al.  HUMAN FACTORS IN ENGINEERING DESIGN , 1947 .

[10]  Hiroshi Udo,et al.  Low back load in two car driver seats , 1997 .

[11]  Subhash Rakheja,et al.  Whole-body vertical biodynamic response characteristics of the seated vehicle driver: measurement and model development , 1998 .

[12]  Masaaki Katsumata,et al.  Evaluation of Seating Comfort , 1982 .

[13]  Richard R. Thompson,et al.  THE DYNAMIC CHARACTERISTICS OF AUTOMOBILE SEATS WITH HUMAN OCCUPANTS , 1977 .

[14]  Bush Ca,et al.  Study of pressures on skin under ischial tuberosities and thighs during sitting. , 1969 .

[15]  A K Lund,et al.  Observed use of automatic seat belts in 1987 cars. , 1989, Accident; analysis and prevention.

[16]  D Ng,et al.  Evaluation of an intelligent seat system. , 1995, Applied ergonomics.

[17]  P C Cryer,et al.  A review of work-related fatal injuries in New Zealand 1975-84--numbers, rates and trends. , 1987, The New Zealand medical journal.

[18]  William S. Marras,et al.  Measurement of Seat Pressure Distributions , 1987 .

[19]  J D GARNER,et al.  An analysis of sitting areas and pressures of man. , 1962, [Report]. Civil Aeromedical Research Institute.

[20]  G. J. Gouw,et al.  A study of hand grip pressure distribution and EMG of finger flexor muscles under dynamic loads. , 1995, Ergonomics.

[21]  Payne Pr.  Method to quantify ride comfort and allowable accelerations. , 1978 .

[22]  O. Lindan,et al.  PRESSURE DISTRIBUTION ON THE SURFACE OF THE HUMAN BODY. I. EVALUATION IN LYING AND SITTING POSITIONS USING A "BED OF SPRINGS AND NAILS". , 1965, Archives of physical medicine and rehabilitation.

[23]  Virendra Tewari,et al.  Tractor ride vibration—A review , 1995 .

[24]  R R COERMANN,et al.  The Mechanical Impedance of the Human Body in Sitting and Standing Position at Low Frequencies , 1962, Human factors.

[25]  Roshan Shishoo,et al.  Measuring methods for comfort rating of seats and beds , 1997 .

[26]  H.-K. Jang,et al.  The effect of phase of differential vertical vibration at the seat and feet on discomfort , 1999 .

[27]  W Frisina,et al.  Pressure mapping: a preliminary report. , 1970, Journal of biomechanics.

[28]  E. Stauffer,et al.  Comparison of pressure distribution qualities in seat cushions. , 1971, Bulletin of prosthetics research.

[29]  P M Bongers,et al.  Long-term sick leave and disability pensioning due to back disorders of tractor drivers exposed to whole-body vibration , 1990, International archives of occupational and environmental health.

[30]  R. Ortengren,et al.  Lumbar disc pressure and myoelectric back muscle activity during sitting. II. Studies on an office chair. , 1976, Scandinavian journal of rehabilitation medicine.

[31]  Yiming Zhou,et al.  Design principles of wheeled-tractor driver-seat static comfort , 1990 .

[32]  E. I. Odell,et al.  Deformations and Stresses in Soft Body Tissues of a Sitting Person , 1978 .

[33]  G. J Gruber,et al.  Relationship between whole-body vibration and morbidity patterns among motor coach operators , 1974 .

[34]  N. C. Petersen.  The Development of Pressure Sores During Hospitalisation , 1976 .

[35]  Charles W. Suggs,et al.  Application of a Dynamic Simulator in Seat Testing , 1970 .

[36]  C A Bush,et al.  Study of pressures on skin under ischial tuberosities and thighs during sitting. , 1969, Archives of physical medicine and rehabilitation.

[37]  M. J. Griffin,et al.  The dynamic characteristics of automobile seats with human occupants , 1978 .

[38]  H. Mertens,et al.  Nonlinear behavior of sitting humans under increasing gravity. , 1978, Aviation, space, and environmental medicine.

[39]  P R Payne.  Method to quantify ride comfort and allowable accelerations. , 1978, Aviation, space, and environmental medicine.

[40]  K C Parsons,et al.  Vibration and comfort. I. Translational seat vibration. , 1982, Ergonomics.

[41]  Subhash Rakheja,et al.  Study of human–seat interface pressure distribution under vertical vibration , 1998 .

[42]  P M Bongers,et al.  Self-reported back pain in tractor drivers exposed to whole-body vibration , 1990, International archives of occupational and environmental health.

[43]  Rani Lueder,et al.  Hard facts about soft machines : the ergonomics of seating , 1994 .

[44]  Subhash Rakheja,et al.  An Analytical and Experimental Investigation of the Driver-Seat-Suspension System , 1994 .

[45]  D S Drummond,et al.  A study of pressure distributions measured during balanced and unbalanced sitting. , 1982, The Journal of bone and joint surgery. American volume.